1. Field of the Invention
This invention relates to an inner sliding or secondary door and temperature control system and method and more particularly, to a secondary door used to facilitate reducing thermal loss and maintaining a temperature in a storage area of a vehicle or trailer within a predetermined or desired temperature range.
2. Description of the Prior Art
During delivery of products, such as frozen food or chilled beverages, delivery drivers are currently required to repeatedly open and close a door on the vehicle or trailer that leads to, for example, a compartment on the vehicle or trailer. With some vehicles, the door is a pivoting or swinging side door on a side of the vehicle. Sometimes a switch shuts down the refrigeration unit, commonly referred to as a “reefer” unit, while the door is open. This is to prevent the refrigeration unit from condensing and being overcome by condensation resulting from the outside warm air which enters the storage compartment when the door is open. When the outside warm air reaches the refrigeration unit, while the unit is running, the warm air will eventually cause the refrigeration unit to “ice up” or “freeze up” and thereby prevent it from blowing cold air and cooling the storage compartment.
In instances where a door switch is used to control the reefer unit, the freezing up phenomenon can be reduced or avoided. However, such systems typically require that the driver open and shut the swinging door on the side of the vehicle each time the driver enters or leaves the storage area of the vehicle. Depending on the size and quantity of product to be delivered, this can result in the opening and closing of the swinging door multiple times, such as 10 times or more, for each delivery.
Because of the nuisance to having to repeatedly open and close the swinging side door, some drivers will typically leave the swinging side door open during the entire delivery process, even if they are not authorized to or are prohibited from doing so. This action most easily is compared to leaving a refrigerator door open for a long period of time. In general, a substantial loss of some, most or all of the cold air from the storage compartment area will occur. The increase in temperature in the storage area has an adverse effect on the quality of the product or cargo stored in the storage compartment.
In vehicles or trailers that are not equipped with door switches, the reefer or refrigeration unit will continue to run regardless of whether the door is open or closed. During quick deliveries, or when the outside temperature is cold, the unit will typically not freeze up the storage compartment area, but the storage compartment area will lose all the cold air during delivery and the reefer unit will continue to run in an attempt to regain the desired or optimal temperature in the storage compartment area. When it is warm outside the storage compartment area, the reefer unit in many cases freezes up during delivery. Once this happens, the reefer unit must be manually defrosted, which can require ½ hour to 1 hour or more to manually defrost the reefer unit. During the entire time that the reefer unit is manually defrosting, there is no cooling of the storage compartment area, which means that the temperature inside the storage compartment area could reach levels that are critical in that they can cause food spoilage or damage to the goods being transported. This is especially a problem if the driver leaves the door open or circumvents its closing.
Even in cases where there is a shut-off switch, once the swinging side door is shut again, the reefer unit will have to run much harder and continuously to achieve the desired temperature in the storage compartment area.
There is, therefore a need to provide a simplified system and method for reducing or eliminating one or more of the problems with the prior art.